Remove hold of snatch write lock during present (#8608)

Author: cwfitzgerald

CHANGELOG.md

@@ -203,6 +203,7 @@ By @cwfitzgerald in [#8609](https://github.com/gfx-rs/wgpu/pull/8609).
 - The `STORAGE_READ_ONLY` texture usage is now permitted to coexist with other read-only usages. By @andyleiserson in [#8490](https://github.com/gfx-rs/wgpu/pull/8490).
 - Validate that buffers are unmapped in `write_buffer` calls. By @ErichDonGubler in [#8454](https://github.com/gfx-rs/wgpu/pull/8454).
 - Add WGSL parsing for mesh shaders. By @inner-daemons in [#8370](https://github.com/gfx-rs/wgpu/pull/8370).
+- Shorten critical section inside present such that the snatch write lock is no longer held during present, preventing other work happening on other threads. By @cwfitzgerald in [#8608](https://github.com/gfx-rs/wgpu/pull/8608).
 
 #### naga
 

wgpu-core/src/present.rs

@@ -293,7 +293,11 @@ impl Surface {
             .take()
             .ok_or(SurfaceError::AlreadyAcquired)?;
 
-        let result = match texture.inner.snatch(&mut device.snatchable_lock.write()) {
+        let mut exclusive_snatch_guard = device.snatchable_lock.write();
+        let inner = texture.inner.snatch(&mut exclusive_snatch_guard);
+        drop(exclusive_snatch_guard);
+
+        let result = match inner {
             None => return Err(SurfaceError::TextureDestroyed),
             Some(resource::TextureInner::Surface { raw }) => {
                 let raw_surface = self.raw(device.backend()).unwrap();
@@ -337,7 +341,11 @@ impl Surface {
             .take()
             .ok_or(SurfaceError::AlreadyAcquired)?;
 
-        match texture.inner.snatch(&mut device.snatchable_lock.write()) {
+        let mut exclusive_snatch_guard = device.snatchable_lock.write();
+        let inner = texture.inner.snatch(&mut exclusive_snatch_guard);
+        drop(exclusive_snatch_guard);
+
+        match inner {
             None => return Err(SurfaceError::TextureDestroyed),
             Some(resource::TextureInner::Surface { raw }) => {
                 let raw_surface = self.raw(device.backend()).unwrap();